Attachment of a spiraled paraffin scraper to a sucker rod is generally known in the art as evidenced by U.S. Patents to Troutman, U.S. Pat. No. 3,410,349; Polson U.S. Pat. No. 2,772,741; Triplehorn U.S. Pat. No. 2,733,768 and 2,928,473; Neumeyer U.S. Pat. No. 1,639,660; Winegar U.S. Pat. No. 2,979,133; and Crayel U.S. Pat. No. 2,453,199.
In Troutman, the scrapers are attached to the rod by a U-band having tabs placed through slots and bent back to mechanically secure the scraper and U-band to one another and to the rod. In Polson the scraper and the U-band are directly welded to one another, with there being no provision for protecting the underlying surface of the sucker rod, and accordingly, the hardness as well as the alloy composition might be changed as the temperature of the rod surface exceeds a certain known value.
Schellsted et al U.S. Pat. No. 3,499,210 teaches a method of mounting a protector on a drill pipe. The protector is in the form of a split sleeve 20 having a slot 34 formed internally thereof within which a back-up strip 35 is received; and thereafter a bead 44 of welding then reattaches the confronting ends 31 of the sleeve 20 together. As the sleeve cools, it is heat shrunk about the drill pipe.
Reference is made to these previously issued patents for further background of the present invention, as well as to the references cited therein.
The present invention differs from the above cited art of record in that a sucker rod and paraffin scraper combination, sometime referred to as a paraffin scraper and rod guide, is arranged in spaced relationship along a string of sucker rod, in alternating relationship with respect to one another, so that adjacent scrapers may be provided with a right handed and left handed pitch spiral about the rod axis, thereby eliminating any tendency of the rods to unscrew respective to one another, and thereby providing a balanced rod string. More distinctly, each scraper assembly is provided with a spiral blade having opposed ends which terminate in projecting tabs. The tabs are formed by cut-outs. A U-band of limited longitudinal length is bent about the rod surface with the confronting edges thereof being placed closely adjacent to one of the tabs located on the scraper. A heat shield underlies both the confronting edge portions of the U-band and further includes a slot within which the tab of the scraper is received. The confronting ends of the U-band are welded to the scraper at a location adjacent to the tabs, while the heat shield isolates and prevents damage to the underlying surface of the sucker rod.